Effects of Temporal Heterogeneity in Nutrient Supply on Intra- And Inter-Genet Competition of a Clonal Herb

[Abstract] Nutrients are often released heterogeneously over time (e.g., in pulses) in natural habitats. Different genotypes of the same plant species may vary in their responses to temporal nutrient heterogeneity so that temporal nutrient heterogeneity may influence intraspecific interactions. To test effects of temporal nutrient heterogeneity on intra-genet (competition between ramets of the same genotype) and inter-genet competition (competition between ramets of different genotypes), we conducted a greenhouse experiment with five genotypes of the clonal herb Hydrocotyle vulgaris. We grew one ramet (no competition), two ramets of the same genotype or two ramets of different genotypes in a pot and supplied the pot with the same total amount of nutrients either homogeneously or heterogeneously. Results showed that temporal nutrient heterogeneity affected the growth and biomass allocation of some genotypes, but had no impact on those of other genotypes of H. vulgaris. These suggested that responses to temporal nutrient heterogeneity were different between genotypes of H. vulgaris. Temporal nutrient heterogeneity had little effect on intra-genet competition of H. vulgaris likely because ramets of the same genotype did not differ in their responses to temporal nutrient heterogeneity. However, temporal nutrient heterogeneity increased the competitive ability of the genotype of H. vulgaris with higher plant productivity. We conclude that temporal nutrient heterogeneity can influence intraspecific interactions of the clonal plant H. vulgaris by altering inter-genet competition, and this effect may further change population dynamics of the plant.